If you recently lost a slew of Facebook friends, it probably wasn't a glitch. Go back and look at your timeline because the chances are good it's your own fault.

That's what a new study from Nielsen seems to indicate anyway. The group surveyed about 2,000 adults to learn why Facebook users add and remove friends, and the results may surprise you.

The top reasons people get the boot? More than half cited "offensive comments," while 41 percent said it was because they didn't know the person well.

And it seems no one likes being treated as a bank account, either. More than a third ditched a Facebook friend because that person was trying to sell them something.

Other things that can get you unfriended include depressing comments, lack of interaction, political comments and updating your profile too often (or, oddly, not often enough).

So, what are you supposed to do to become Facebook friends with someone? Eighty-two percent of respondents said the best route is to know them in real life, followed by 60 percent who were swayed if you had mutual friends. About one in ten people also friend those in their business networks.

If you're attractive, 8 percent will friend you based solely on that. Don't let it go to your head, though, because 7 percent of people said they accept all friend requests anyway.

Having trouble visualizing this? Check out the rest of the study below.